Delay loading of composer picture preview icons until widget is shown

src/app/composer/qgscomposer.cpp

@@ -1134,6 +1134,14 @@ void QgsComposer::showEvent( QShowEvent* event )
       mapIt.key()->update();
     }
     mMapsToRestore.clear();
+
+    //create composer picture widget previews
+    QList< QgsComposerPictureWidget* >::iterator picIt = mPicturePreviews.begin();
+    for ( ; picIt != mPicturePreviews.end(); ++picIt )
+    {
+      ( *picIt )->addStandardDirectoriesToPreview();
+    }
+    mPicturePreviews.clear();
   }
 
 #ifdef Q_WS_MAC
@@ -1382,6 +1390,14 @@ void QgsComposer::addComposerPicture( QgsComposerPicture* picture )
   }
 
   QgsComposerPictureWidget* pWidget = new QgsComposerPictureWidget( picture );
+  if ( isVisible() )
+  {
+    pWidget->addStandardDirectoriesToPreview();
+  }
+  else
+  {
+    mPicturePreviews.append( pWidget );
+  }
   mItemWidgetMap.insert( picture, pWidget );
 }
 

src/app/composer/qgscomposer.h

@@ -27,6 +27,7 @@ class QgsComposerArrow;
 class QgsComposerLabel;
 class QgsComposerLegend;
 class QgsComposerPicture;
+class QgsComposerPictureWidget;
 class QgsComposerScaleBar;
 class QgsComposerShape;
 class QgsComposerAttributeTable;
@@ -322,6 +323,7 @@ class QgsComposer: public QMainWindow, private Ui::QgsComposerBase
 
     //! We load composer map content from project xml only on demand. Therefore we need to store the real preview mode type
     QMap< QgsComposerMap*, int > mMapsToRestore;
+    QList< QgsComposerPictureWidget* > mPicturePreviews;
 
     QDockWidget* mItemDock;
     QDockWidget* mUndoDock;

src/app/composer/qgscomposerpicturewidget.cpp

@@ -30,7 +30,7 @@
 #include <QSettings>
 #include <QSvgRenderer>
 
-QgsComposerPictureWidget::QgsComposerPictureWidget( QgsComposerPicture* picture ): QWidget(), mPicture( picture ), mPreviewInitialized( false )
+QgsComposerPictureWidget::QgsComposerPictureWidget( QgsComposerPicture* picture ): QWidget(), mPicture( picture )
 {
   setupUi( this );
 
@@ -44,8 +44,6 @@ QgsComposerPictureWidget::QgsComposerPictureWidget( QgsComposerPicture* picture
 
   mPreviewListWidget->setIconSize( QSize( 30, 30 ) );
 
-  //add preview icons on demand in showEvent()
-
   connect( mPicture, SIGNAL( itemChanged() ), this, SLOT( setGuiElementValues() ) );
   connect( mPicture, SIGNAL( rotationChanged( double ) ), this, SLOT( setGuiElementValues() ) );
 }
@@ -261,17 +259,6 @@ void QgsComposerPictureWidget::on_mRotationFromComposerMapCheckBox_stateChanged(
   mPicture->endCommand();
 }
 
-void QgsComposerPictureWidget::showEvent( QShowEvent * event )
-{
-  refreshMapComboBox();
-  if ( !mPreviewInitialized )
-  {
-    addStandardDirectoriesToPreview();
-    mPreviewInitialized = true;
-  }
-  QWidget::showEvent( event );
-}
-
 void QgsComposerPictureWidget::on_mComposerMapComboBox_activated( const QString & text )
 {
   if ( !mPicture || text.isEmpty() || !mPicture->useRotationMap() )
@@ -481,6 +468,8 @@ int QgsComposerPictureWidget::addDirectoryToPreview( const QString& path )
 
 void QgsComposerPictureWidget::addStandardDirectoriesToPreview()
 {
+  mPreviewListWidget->clear();
+
   //list all directories in $prefix/share/qgis/svg
   QStringList svgPaths = QgsApplication::svgPaths();
   for ( int i = 0; i < svgPaths.size(); i++ )
@@ -536,3 +525,10 @@ bool QgsComposerPictureWidget::testImageFile( const QString& filename ) const
   QString formatName = QString( QImageReader::imageFormat( filename ) );
   return !formatName.isEmpty(); //file is in a supported pixel format
 }
+
+void QgsComposerPictureWidget::showEvent( QShowEvent * event )
+{
+  Q_UNUSED( event );
+  refreshMapComboBox();
+}
+

src/app/composer/qgscomposerpicturewidget.h

@@ -33,6 +33,9 @@ class QgsComposerPictureWidget: public QWidget, private Ui::QgsComposerPictureWi
     QgsComposerPictureWidget( QgsComposerPicture* picture );
     ~QgsComposerPictureWidget();
 
+    /**Add the icons of the standard directories to the preview*/
+    void addStandardDirectoriesToPreview();
+
   public slots:
     void on_mPictureBrowseButton_clicked();
     void on_mPictureLineEdit_editingFinished();
@@ -45,21 +48,19 @@ class QgsComposerPictureWidget: public QWidget, private Ui::QgsComposerPictureWi
     void on_mRotationFromComposerMapCheckBox_stateChanged( int state );
     void on_mComposerMapComboBox_activated( const QString & text );
 
+  protected:
+    void showEvent( QShowEvent * event );
+
   private slots:
     /**Sets the GUI elements to the values of mPicture*/
     void setGuiElementValues();
 
-  protected:
-    void showEvent( QShowEvent * event );
-
   private:
     QgsComposerPicture* mPicture;
-    bool mPreviewInitialized;
 
     /**Add the icons of a directory to the preview. Returns 0 in case of success*/
     int addDirectoryToPreview( const QString& path );
-    /**Add the icons of the standard directories to the preview*/
-    void addStandardDirectoriesToPreview();
+
     /**Tests if a file is valid svg*/
     bool testSvgFile( const QString& filename ) const;
     /**Tests if a file is a valid pixel format*/

src/ui/qgscomposerpicturewidgetbase.ui

@@ -33,8 +33,8 @@
        <rect>
         <x>0</x>
         <y>0</y>
-        <width>327</width>
-        <height>585</height>
+        <width>317</width>
+        <height>577</height>
        </rect>
       </property>
       <attribute name="label">
@@ -79,6 +79,9 @@
             <property name="isWrapping" stdset="0">
              <bool>true</bool>
             </property>
+            <property name="resizeMode">
+             <enum>QListView::Adjust</enum>
+            </property>
             <property name="gridSize">
              <size>
               <width>30</width>